1. Technical Field
The present invention generally relates to force sensing systems. More particularly, the present invention relates to force sensor assemblies used in robotic applications. Even more particularly, the present invention relates to single axis robot force sensor assemblies having the capability of sensing compressive and tensile forces associated with robotic applications.
2. Background Information
A problem associated with robot technology today is the lack of simple and compact robot force sensing systems, which after detecting one or more predetermined forces associated with a robot's motion, have the capability of directing the robot to perform alternative motions or tasks. Another problem is the lack of devices which permit a user the opportunity to simply adjust the sensitivity of the forces desired to be detected. These problems are especially prevalent in sensing compressive and tensile forces along a single axis.
While conventional load cells have been used in the past for sensing single axis forces in robotic applications, such devices are typically cumbersome and complex. Moreover, conventional load cell devices and other force sensing devices do not have circuitry which is physically incorporated as part of the devices. Furthermore, conventional load cells do not have the ability to adjust the sensitivity of the forces desired to be sensed. As a result, the commercial incorporation of conventional load cells into robotic machinery for sensing single axis compressive and tensile forces is not feasible.
There also exist multiple axis force sensing devices, which not only measure axial forces, but also measure moment forces associated with robotic applications. However, these devices are typically complex, requiring sophisticated electronic circuitry to be physically separated from the force sensor assembly. Also, multiple axis force sensing devices generate a data stream of information, most of which is not needed in sensing only compressive and tensile forces along a single axis. Because of their complexity and size (and expense), it is not feasible or commercially sensible to employ such devices for detecting only single axis compressive and tensile forces.
Also, most commercially available robots include emergency overload detection systems (e.g, servo error) which shut down the robot upon reaching an overload condition, i.e., when the system surpasses a pre-determined threshold force. However, presently existing overload systems are limited in their applications because of a lack of sensitivity in detecting small forces. Typically, emergency overload detection systems shut down the system upon sensing a large force. Also, these systems do not permit the robot to perform an alternate motion or task upon reaching the overload condition. Once the overload condition is detected, the robot automatically shuts down and it is thereafter necessary for an operator to clear the error on the robot control system. At times, it may be necessary for the operator to physically remove an obstruction which caused the overload condition. Once the overload condition is corrected, the operator may then re-start operation of the robot. This procedure, however, is timely and costly.
Until now, there have been no known force sensor assemblies which may be easily and simply incorporated and packaged for use with robotic machinery for sensing devices along a single axis.
The present invention was the result of the recognition of a need in the robotic industry for a single axis force sensor which senses compressive or tensile forces along a single axis, and in response to sensing a predetermined force, signals the robot controller to direct the robot to perform an alternate motion or task. The structure of the present invention contains a solution to the aforementioned problems.